Electrical signaling system.



A. D. T. LIBBY. ELECTRICAL SIGNALING SYST APPLICATION FILED MAY 12, 1

Patented May 18, 1909.

. UNITED STATES ALBION ,D; T. LIBBY, OF ELYRIA, OHIO, ASSIGNOR TO THE DEAN ELECTRIC ELYRIA, OHIO, A CORPORATION OF OHIO.

TENT oririon 7 ELECTRICAL SIGNALING sys'rmr.

' nalin Systems, of which the following is a s ci cation, reference being had therein to te accompanying drawing.

My invention relates to electric signaling systems, and particularly to those in which selection is to be accomplished means of differences in the character or conditions of the signaling current or its application;

i The invention contemplates the use of transformers and of circuit-changers or interrupters therefor, and the objects of the invention are to simplify the a 'paratus employed, while increasing, the e ciency of the same and of the system in which it is employed. 1

More specifically stated, my invention relates to what are known as harmonic or poly-frequency systems of signaling, in which the current supplied to the line-circuits is produced in thesecondary windings of transformers,- the Rifllllfil'leSOf which are controlled by interrupters or pole-changers. In the embodiment 0 battery or-otheflr source of direct current supplies all the energy for both signaling and signal control through the motors. 1n accordance with established usage in so-called harmonic systems, an assemblage of four units 'is employed, each comprising aturied vibrating pole-changer having a motor mag-- net and controlling the primary ener y of a suitable transformer, the secondary 0 which 4 supplies the line-signaling current.

The principal characteristic features of my invention are nine in number, as follows :v

-F1-rst:-Th e use of a transformer with a double primary, each half of which has the 15 samenumben'of turns, or in other words, a

parallel winding so as to havethe same quantitative efiect on the secondary winding when the same amount of current flows in either coil.. r

.1 Secondz-A vibrating mechanism for-al-l 5 second primary coil so connetced that cur-J Specification of Letters Patent. Application filed May 12, 1906. Serial Nd/316,4 9 1.

the invention which I' p 30 shall hereinafter describe, a single.v main rent will flow-therein in an o posite direction from that in the first, there y producing an alternating magnetizing effect in the transformer core. v

Third:The use of condensers placed across the primaries of these coils to-assist stationary contacts. This obviates the ne the armature and using flexible leading-in conductors forthe same.

Fifthz-The mechanical armatures by mounting them on different sized springs and by the use of difierent sized weights; For example, the lowest frequency vibrator is mounted on a thin spring of very li ht' tension and has a large weight. The ot er vibrators have thicker "springs and smaller weights.

SiX-th:The adjustment of the motor winding, which controls a vibrator armature, to the frequency for which the armature is ably made of high resistance, wh' e the higher frequency vibrators have windings of the lowest resistance. By this means it is possible to give a uniform strength of movetors. Y

Seventh-The adjustment-of the trans-- formers to the different frequencies by regulating the amount of iron in the cores, as Well as the design of the windings. The low frequency transformer has a arge amount of iron and the others a lesser amount, the

of iron,

Eighth :-The adjustment of the capacity of eachcondenser to suit the frequency as well as the characteristics of its transformer. For example, a low fre uencytransfor mer has low capacity con, ensers across its primaries, while the others have large capIacities. k 'o inth:-The adjustment of the voltage of the secondaries of the. transformers to c0nform to the requirements of ,the harmonic partyline signal receivers, the low frequency; secondary. tension bein about fifty (50a COMPANY, OF

' cessity of having insulated parts attached to.

tuned. A low frequency winding is refer ment to the armatures for the various vibrahighestfreq'uency having the smallest amount volts, for example, and t e others in propor- Patented. May 18, 19095 L in the action thereof as well as to cut down tuning of the 12 represent a line-circuit extending-from immaterial to the signaling circuits, but they second;'the rin er Q at station A has a natural period 0 fifty cycles per second; and

' tion thereto, the highest frequency about one hundred and seventy-five (175) volts. I This invention is part'cularly useful in connection with party-lines selective ringing in exchange systems of telephones. Forconvenience, therefore, I shall illustrate and describe the apparatus and circuits as they are applied to such a system. i

The invention is illustrated in-the accompanying drawing, in which the diagram shows a line-circuit extending to four stations, the operators circuit-terminal whereby connection is eflected with said line-circuit, the central ofiice equipment of gener'atin units, and finally the switches by means 0 which the same are connected through the terminal to the line.

Referring to the drawing, the numerals the central. station E to the four sub-sta tions A, A ,,A and A. The telephone sets at these substations are not shown, being are of any usual or suitable type, their cir; cuits being disconnected or opened when not in use. At each station is a ringer Q, Q Q? or Q bridged across the line-wires, 12 in series with the condenser C, C C or the bridge wires being indicated at =34. The ringers, and if deslred the condensers, at the several stations are adjusted for particular frequencies. As indicated in the dia ram, the ringer Q, at station A is tuned so t at it will vibrate with a free natural eriod of 16.6 cycles per second; the ringer 1 at station A -vibrates with a period of 33.3 cycles per finally theringer Q at station A has a natural period of 66.6 cycles per second.

The line-wires terminate at the exchange or central station Eu on contacts of aspringjack J, with which t e plug P cooperates to connect thecord-conductors 56 to the linewires 1'2. These cord conductors may lead to any desired talking andsubsidiary apparatus, all of which is omitted, for the simplicity in the drawing. I have-linnted my showing to the apparatus particularly needed for the practice of this invention, which is the selective ringing key K. This key consists as shown of four sets of springs k, W, 7: and k, all normally closed upon anvil contacts by which the cord-circuit is completed through them in series. It. "will. be understood, of course, that this type of key, and other s ecific apparatus herein illustrated, are use for convenience, and are not to betaken as limitin the invention in any way. -Any suitable icy may be employed, and any suitable design ofcircuits not incompatible with the essential portions re aches ing tied together.

of the enerating units and their circuits. Each 0 the spring keys k, etc., wassumed to have a button or cam by which the springs .may be spread so as to break connection with their-normal anvil or resting contacts and make connection with the outside contacts shown arrangedin pairs at 7'8 910; 11-12; 13-14. Thisarrange v ment of spring contacts is well understood by all those skilled in the art, and the operating cams need no illustration.

The contacts 8, 10, 12 and 14 are joined together by the bus-wire 15, and connected to earth through the wire 16. Their indi- I vidual branches 18202224 may however be carried back to their respective transformer secondaries, if desired, instead of be- The contact 7 is connected by wire 17 to the secondary winding t of the transformer T, designed as ;will

presently appear to produce alternating current at a frequency. of 16.6 cycles and fifty The contact 9 is similarly connected L by wire 19 to the secondary volts.

of transformer '1 designed to furnish current at 33.3 cycles and volts; contact 11 is'connected by wire 21 to the secondary of the transformer T adapted to furnish current at fifty cycles and volts; while contact 13 is connected to the secondary of a transformer T adapted to furnish current at 66.6 cycles and 17.5

volts. Each of these transformers forms a part of a complete unit, these units being respectively designated as M, M M" and M Since the corresponding parts of all the units are similar in their shape, arrangement and connection, a description of one will suffice for all. I will therefore describe the unit M which alone bears detailed reference letters, and afterward I will point out the adjustments and variations in size, etc., by which these units are tuned. Referring then to the unit M this comprises as its essential elements a pole-changer M, with a suitable 'motor to drive the same, and a transformer T Current is supplied to all of the units from'the main battery B through the bus-wire- 25. This battery may conveniently be desi ned to give a voltage of 24, in accordance wit usual practice.

The pole-changer M has a rigid abut- -ment or post m carrying a supportingspring m upon which is secured the vibrating arm m carrying spring-contactsand tuned as to the perio of 1 by the pendulum bob-or weigtitnrfl. The arm or vibrator m" is controlled which has become quite familiar in ordinary vibrating bells. The/winding ofthe magnet is connected on oneside to the bus-wire v25 through the branch wire 26,. and frdm its ts v1bratio'n',.partly by the regulationof the spring m and partly y the motor magnet m, whosewinding is adjusted as toother side a wire 27 passes to the fixed coneflicients togthe indicating letter C, but their 65 tact 28, which coeperates' with' a spring m I secured upon andto the vibrator by means of rivets-m which conveniently pass through the vibrator arm and the spring m, and also through a stiffening strip m thereby securing all the parts together in a simple but highly efficient manner.

K Secured at the lower end of the vibrator 10 are two contact springs m and m each ,with' a stifiening strip or arm, mi and m and 'both sprin s with their stiffening strips secured rigi ly' upon the vibrator arm. by means of rivets m. The vibrator and the three springs m m and m? are all in metallic contact and electrically connected, being grounded 'throu h the sprin m and the abutment m W ich is provi e'd witha suitable ground wire g. As the magnet m attracts the vibrator arm, the contacts m and 28 remain together during the first part of the'movement, but separate at a predetermined fpoint where the spring snaps against the sti ener m The magnet thus loses its ground, and becoming deener" iZed permits the vibrator to swing back unti the contacts m and 28 again come together when the former operation is repeated, and so on indefinitely. It goes without-saying that any 30 suitable switching means may be employed to controlthe circuits of the magnets m, but for the sake of simplicit in the diagram I have omitted all control ing switches,..indi'- eating these magnets in constantly closed circuits. In practice at least one switch is interposed as at X in the figure. i As the vibrator moves back and forth it brings first the one and then the other of the springs or and m against their contacts 30 40 and 29, respectively. The contact 30 is connectedby wire 32 to one end pf the primary winding 2, and the contact 29 is connected by wire 31 to one end of the winding i. The.

other ends of both windin s areconnected together at 33, and thence t rough the common Wire 34 'to the battery. bllSfViI'Q 25. As the vibrator swings back and forth, there'- fore, current will flow alternately throu h one and the other of these windings, by reason of "the outer ends being alternately grounded. The two windings are proportioned and laid on the core of the transformer so as to produce equal but opposite magnetic effects therein; hence their alternating supply of current, by reversing magnetic con itions in the core, (produces alternating electromoti've forces an alternating current in the secondary t and the wire 23. Across the terminals 33 and 35 of th primary winding t I connect a condenser and across the terminals 33 and 36 of the other primary t? I connect a condenser CK The correspon'din condensers in the other units are marks with different co'- connection is the same in each case Having thus described the essential features of each unit, I will now point out the distinguishing difierences between the units. oints Nos. 5, 6, 7, 8-

These are stated as and 9, in the preamb e to this specification. Point 5th is the mechanical tuning of the armatures by the springs and weights. Each 'armature or vibrator m has its period determined by the gage and tension. of the spring m and the mass of the bob m The hlgh-speed vibrator M has a've'ry light bob and a thick spring; while the lowest speed vibrator M has a thin spring and aheavy bob, as shown in the diagram. I should here point out that instead of varying the springs m, I may attain the same result by varying the thickness and tension of the sprin s m",

by grading from a suitable thickness in the vibrator M down to comparative thinness in the vibrator M. I may also combine both of these gradations.

The 6th point is the motor winding. The motor magnet m in the unit M is wound to 200 ohms; in the unit M it is wound to 400 ohms; in the unit M it is wound to 800 ohms and in the unit M it is wound to 2000 ohms.

Thus, it will be noted that speaking approxi= mately the resistance of the motor windings is inversely proportional to thefrequencies desired; The amount of energy supplied to the several vibrators is thus maintained approximately constant. 7 complete cycle of movement of the vibrator requlres a unit of energy, then for a 16 cycle frequency, 16 units of energy are required;

for a 33 cycle frequency, 33 unitsare required, and so on. By regulating themesistance and number of turns in the different motor magnet windin s, the amount of cur= "rent at constant vo tage that will pass through'each magnet, and the number of Assuming that one Y ampere turns with the consequent amount of energy magnetically transmitted to the armature, can be regulated to a nicety.

The 7th point is the adjustment of the transformers. This also is roughly indicated in the diagram, the core i of the transformer T being shown as relatively small, while those of the succeeding units increase'progressively in the amount of iron they contain until the low frequency transformer'T is.

reached in which the amount of iron is the maximum. The principles of transformer design being well understood, it is unnecessary to explain the reasons for this, my invention consisting particularly in the combina tion set forth and not in the design of a par- -ticular transformer.

r The 8th point is the adjustment of the ca-' use secondary voltages of 50, 125, 150 and variations is easily a parent.

' ers,

has 4 m. f.; in the unit M each has 6 m. f., and finally in the unit M each condenser has a capacity of 8- In. f. The reason for these These condensers have a twoold function. They tend to sharpen theaction of the transformby furnishing a leading electromotive force to ncutralize the lag due to inductance,

while at the same time they take u the dischar es from-the coils and so cut own the spar 'ng at the contacts 29- m and 30-41%.

' The 9th voltage ofthe secondaries if whereby for any 'ven frequency an amount of energy will be imparted to the signal actuating magnet or ringer proportional to the work it has to do, and the danger of interference between hi h and low frequency magnets will be largely obviated. t

I find in my system that it is desirable to 175 for the transformers adapted to operate on 16.6, 33.3, 50 and 66.6 cycles per second respectively, and hence such secondary voltages may be said to be approximately proportional to such frequencies.

Without going into any elaborate'mathematical statement, or formulating equations,

I believe I have sufficiently shown that there is for each frequency in this system a condition of resonance both mechanical and electrical for the particular signal receiver intended to be reached, and this condition is maintained without the necessity for any delicate adjustments, all parts being interchangeable and easily manufactured. It

will be observed that there are only two contacts 1n the pole-changer, which is less than in any similar device of which I have knowledge; A third contact is provided for the motor magnet, and all three of these contacts are of the simplest possible design, solidly supported, mechanically and electrically oo'd, without any interposed insulation, and free from battery connections which might produce a short-circuit by accident.

, I am aware that the invention thus described may be incorporated in a great many di fferent fo rms of apparatus, but I do not wish to hunt myself to any specific form, beyond what is necessary to embody the features I point out'as being of the essence of the invention. All minor or non-essential changes I regard as in the scope of the following claims. I shall use the term generating unit in myclaims hereinafter to mean the combination of elements which I have shown for producing a given frequency. The battery, while it is the primary source of energy for this system, serves the same purpose as an exciter in any system of generation. The

' currents which go to line and do the work of signaling are actually generatedin the sec' ondary windings of the transformers, but the primary winding and circuit of each transpoint is the adjustment of the.

formerwith its-vibrator, and its exciting source of constant current, form obvious parts of the complete unit.

' Having thus described my invention, what I claim and desire to secure by Letters Patent of the United States is:

1. In an electrical signaling system, a source of current, a signal-receiving device, and a transformer having a secondary winding connected therewith and two primary windings adapted to produce 0 posite effects on the transformer core an means for alternatelyconnecting such primary windings to such source of current.

2. In an electrical signaling system, a source of current, a signal-receiving device, transforming means in circuit with such device and adapted to be operated from" such source of current and a vibrating member for changing the circuit connections of such transforming means to such source of energy, contacts carried by such member for effecting its own operation and also such circuit changes, such contacts being in electrical connection with each other and with such rality of means adapted to roduce alternating currents of different frequencies, each means comprising a transformer having primary and secondary windings and a circuit controller in such rimary circuit, a signalin device in sucfi secondary circuit, the volume of the cores of such transformers being inversely (proportional to such frequencie's, the secon ary windings ofsuch transformers adapted to delivercurrents at pressures approximately proportional to such frequencies and condensers bridged across the terminals of such primary windings, the capacities of efnch condensers being prpportional to such'frequencies.

5. In an electrical signaling system, a plurality of means ada ted to roduce alternating currents of di erent requencies, each means comprising a transformer havin primaryand secondary windings and a circuit controller in such primary circuit, a signal device in such secondary circu t, the volume of the cores of such transformers being 1nversel proportional to such frequencies, the

secon ary windings of such transformers adapted to deliver currents at pressures, ap-

of such primary windings, the capacities of i such condensers being pro ortional to such 1 frequencies and motor win ings for such circuit controllers of resistances approximately inversely proportional to such frequencies.

6. In an electrical signaling system, a plurality of means adapted to produce periodic currents of different frequencies, each means comprising a transformer having primary and secondary windings and a circuit controlle in such primary circuit, a signaling device in such secondary circuit, the volume of the cores of such transformers being inversely proportional to such frequencies.

7. In an electrical signaling system, a plu rality of means adapted to produce eriodic currents of different frequencies, eac means comprising a transformer having primary and'secondary windings and a circuit controller in such primary circuit, a signaling device in such secondary circuit, the secondary windings of such transformers adapted to deliver currents at ressures approximately proportional to sue frequencies.

8. In an electrical signaling system, a plurality of means adapted to produce eriodic currents of different frequencies, eac 1 means comprising a transformer having primary and secondary windings and a clrcuit con troller in such primary circuit, a signaling device in such secondary circuit and motor.

windings for such circuit controllers of reslstances approximately lnversely proportional to such frequencies.

9. In, an electrical signaling system, a lurality'of means adapted to produce signa ing current comprising circuit changers adapted to vibrate at different frequencies and motor magnets for such clrcuit changers inversely proportional to such frequencies in their magnetic effect. 1

10. In an electrical signaling system, a lurality of means adapted to produce signa ing current of different frequencies comprising circuit changers connected in circuit with a source of current and the primar windings of corresponding transformers an signal devices in circuit with the seconda windings of such transformers and means or delivering currents from such secondary windings at pressures approximately proportional to the frequencies of the currents supplied to the corresponding transformers.

11. In an electrical si naling system, a source of current, a signa receiving device, a transformer having a secondary winding connected therewith and two primary windings adapted to produce opposite effects on the transformer core, and a pole changer for alternately connecting such primary winding to such source of current.

12. In an electrical signaling system, a

I l l 1 l l changer for alternately connecting the other terminals of such primary windings to the other terminal of such source.

13. In an electrical signaling system, a source of current, a signal receiving device, a transformer having a secondary winding connected therewith and two primary windings adapted to produce opposite effects on the transformer core, one terminal of each of such windings ermanently connected to one terminal of such source, and a pole changer consisting in a vibratory member connected to the other terminal of such source, such member adapted as it vibrates to enga 'e contacts connected to the other terminals of the primary windings.

14. In an electrical signaling system; a source'of current, a signal receiving device, a transformer having a secondary winding connected therewith and two primary windings adapted to produce opposite effects on the transformer core, one terminal of each of such windings permanently connected to one terminal of such source, a pole changer, a motor magnet for such pole changer, one terminal of which is connected to one terminal of such source, and a vibratory member in such pole changer, such member 100 adapted as it vibrates to engage contacts connected to the other terminals of the primary windings and of the motor magnet.

15. In an electrical si' aling system, a source of current, a signa receiving device, 1 5 a transformer having a secondary winding connected therewith and two primary windings adapted to produce'opposite effects on the transformer core, a pole changer for nection therewith, and contacts insulated from the base to cooperate with the vibratory contacts, such insulated contacts being connected to one terminal of the motor magnet and to one terminal of each of the 32 primary windings, the other terminals of the motor magnet and primary windings bein connected together and to the other terminal of the source.

In testimony whereof I affix my signature in presence of two witnesses.

ALBION D. T. LIBBY. Witnesses:

WM. W. DEAN, F. L. MARTIN. 

